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EP0708721B1 - Hydraulic braking system with skid and drive slip control - Google Patents

Hydraulic braking system with skid and drive slip control Download PDF

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Publication number
EP0708721B1
EP0708721B1 EP19940921652 EP94921652A EP0708721B1 EP 0708721 B1 EP0708721 B1 EP 0708721B1 EP 19940921652 EP19940921652 EP 19940921652 EP 94921652 A EP94921652 A EP 94921652A EP 0708721 B1 EP0708721 B1 EP 0708721B1
Authority
EP
European Patent Office
Prior art keywords
valve
suction
pressure
brake system
pressure chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19940921652
Other languages
German (de)
French (fr)
Other versions
EP0708721A1 (en
Inventor
Erhard Beck
Hans-Dieter Reinartz
Albrecht Otto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ITT Automotive Europe GmbH
Continental Teves AG and Co OHG
Original Assignee
ITT Automotive Europe GmbH
Alfred Teves GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19934324689 external-priority patent/DE4324689A1/en
Priority claimed from DE19934326389 external-priority patent/DE4326389A1/en
Application filed by ITT Automotive Europe GmbH, Alfred Teves GmbH filed Critical ITT Automotive Europe GmbH
Publication of EP0708721A1 publication Critical patent/EP0708721A1/en
Application granted granted Critical
Publication of EP0708721B1 publication Critical patent/EP0708721B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/10—Valves; Arrangement of valves
    • F04B53/12—Valves; Arrangement of valves arranged in or on pistons
    • F04B53/125—Reciprocating valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/40—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
    • B60T8/4031—Pump units characterised by their construction or mounting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
    • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
    • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
    • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
    • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/10—Valves; Arrangement of valves
    • F04B53/102—Disc valves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2496—Self-proportioning or correlating systems
    • Y10T137/2559—Self-controlled branched flow systems
    • Y10T137/2564—Plural inflows
    • Y10T137/2567—Alternate or successive inflows

Definitions

  • the present invention relates to a hydraulic brake system of the type described in the preamble of the main claim.
  • a generic brake system is known from DE 34 39 408 C1.
  • the known brake system works in the brake slip control mode according to the return feed principle.
  • the return pump is self-priming and, in the case of brake slip control, sucks from the low-pressure accumulator via a first suction valve and a first suction line, while it draws in from the pressure medium container via a second suction valve and a second suction line provided with a changeover valve via the brake line and the master brake cylinder.
  • the parallel connection of the suction valves has the advantage that only one suction valve has to be overcome in both a brake slip control and a traction control system. Throttling effects are thereby reduced, so that the delivery capacity of the pump is improved.
  • Such a pump is known for example from DE 40 27 794 A1.
  • the pump described is designed as a radial piston pump and has a delivery piston on which the valve seat for the suction valve is molded.
  • the closing element of the suction valve is acted upon by a valve spring which is supported in a housing-fixed manner.
  • the preload of the valve spring increases.
  • the preload of the valve spring is therefore greatest, so that an opening pressure of the suction valve which is substantially higher than the bottom dead center of the piston has to be overcome.
  • the object of the present invention is to provide a structurally advantageous design of a generic brake system.
  • Another object of the present invention is to provide a hydraulic pump in which the suction valve is less pressurized near the top dead center of the delivery piston than near the bottom dead center.
  • a particularly favorable spatial arrangement results if one of the suction valves is located on the displaceable pump piston, while the other is arranged fixed to the housing.
  • the difference in the admission pressures, which exists between a brake slip control and a traction control, can take place through different designs of the opening cross sections of the suction valves.
  • the load on the closing member of the second suction valve can be reduced by counteracting a second compression spring, which is designed to be weaker than the compression spring arranged between the closing members.
  • variable locking of the valve spring is achieved by means of a lever arrangement on the pump.
  • the valve spring In the vicinity of the top dead center of the delivery piston, the valve spring is held by the lever elements, so that suction with a low admission pressure is possible from the top dead center at the beginning of a piston movement.
  • the entire pressure difference between the suction connection and the pressure chamber contributes to the acceleration of the pressure medium, without loss of the valve admission pressure to be overcome.
  • the valve spring is already largely relaxed anyway, so that further action by the lever elements is unnecessary.
  • variable force dependent on the stroke of the delivery piston can be generated either by the compression spring returning the delivery piston or by a stop fixed to the housing.
  • the features according to claim 10 allow installation of the lever elements with an assembly process.
  • the one-piece production of all lever elements and the connecting pieces arranged between them eliminates the need to preassemble the lever arrangement.
  • This one-piece transmission element is particularly inexpensive as a stamped sheet metal part.
  • valve spring it is envisaged to superimpose a further force on the force exerted by the valve spring, the size and direction of which may vary depending on the speed and / or acceleration of the delivery piston and in this way facilitate opening of the valve during the suction stroke.
  • the friction element can be arranged, for example, in the region of an element guiding the closing element.
  • An additional force proportional to the speed of the delivery piston can be achieved if the closing member is connected to a body which has a large flow resistance during the movement from the top to bottom dead center.
  • This body is advantageously designed to be more aerodynamic in the opposite direction.
  • the aerodynamically unfavorable body can be made in one piece with the closing member.
  • a further, easily implementable measure of exerting an additional force on the closing element is to connect the closing element to an inertial body, the mass of which is large compared to the mass of the closing element.
  • the inertial body can advantageously be arranged in the dead space caused by the overall length of the valve closing spring. Additional construction volume is therefore not necessary.
  • a constant prestressing force acting on the closing member over the entire suction stroke of the delivery piston can be achieved if the mass of the inertial body is matched to a design speed of a motor driving the pump.
  • This adjustment is carried out in such a way that the force caused by the inertial mass and the variable portion of the spring force caused by the compression of the valve spring are so matched to one another at a predetermined working speed that they cancel each other out.
  • the pump output can thus be maximized at this predetermined working speed.
  • the master brake cylinder 201 is connected to the pressure medium reservoir 202.
  • the brake line 203 leads from the master brake cylinder 201 via the electromagnetically actuated, normally open isolating valve 204 and the likewise electromagnetically actuated, normally open inlet valve 205 to the wheel brake cylinder 206 of a driven wheel.
  • the return line 207 runs from the wheel brake cylinder 206 via the electromagnetically actuated, normally closed outlet valve 208 to the low-pressure accumulator 209. From this, the pressure medium is conveyed via the first suction line 210 by the pump 211 into the pressure line 212, which between the isolating valve 204 and the inlet valve 205 in the brake line 208 opens.
  • the second suction line 213 of the pump 211 is connected to the brake line 203.
  • a changeover valve 214 which is actuated hydraulically by the pressure of the master brake cylinder 201 and is open without pressure, is inserted into the second suction line 213.
  • the pump 211 sucks the pressure medium from the pressure medium container 202 for traction control via the brake line 203 and the master brake cylinder 201 or whether the second suction line 213 is connected directly to the pressure medium container 202, since the master brake cylinder 201 is in the unactuated state from Pressure medium can be flowed through.
  • the housing 215 of the pump 211 has a continuous, simply stepped bore 216.
  • the piston 219 is guided to the atmosphere in a manner sealed against the bore wall.
  • the bore section 218 of larger diameter is closed pressure-tight with the screw cap 235.
  • the pressure chamber 222 in which the return spring 221 is arranged, spans between the bore-inner end of the piston 219 and the expansion stage 220. This is supported on the valve seat 233 of the second suction valve 231 and acts on the inside of the bore of the piston 219 towards the atmosphere.
  • An axial blind bore 223 is guided into the piston 219 from the inside of the bore.
  • the first suction valve 227 is attached at the mouth of the blind bore 223 into the pressure chamber 222.
  • the valve seat 229 of the first suction valve 227 is integrally formed on the piston end, while the closing member 228 is acted upon by the valve spring 230 toward the valve seat.
  • this valve spring 230 is supported on the valve seat 233 of the second suction valve.
  • the valve seat 233 of the second suction valve 231 is positively connected to the screw cap 235 by the locking lugs 236.
  • the valve spring 234 of the second suction valve 231 is arranged between the valve seat 233 and the screw cap 235. It acts on an annular disc which is connected to a plunger formed on the closing element 232 of the second suction valve 231.
  • valve spring 234 is also supported on the valve seat 233 and acts on the annular disc towards the screw cap 235.
  • the closing member 232 is designed in the form of a part of a sphere, the plunger being attached in the middle of the spherical surface.
  • the admission pressure of the two suction valves 227 and 231 is determined on the one hand by the diameter of the valve seats 229 and 233 and on the other hand by the spring forces of the valve springs 230 and 234. In this case, a pre-pressure at or above atmospheric pressure has proven itself for the first suction valve 227, since in this way a pressure drop below atmospheric pressure in the low-pressure accumulator 209 and in the wheel brake cylinder 206 is prevented. Such a precautionary measure is not necessary for the suction valve 231, but rather the best possible delivery rate is to be achieved.
  • the upstream pressure of this second suction valve 231 is therefore below atmospheric pressure, preferably around 0.2 bar.
  • FIG. 2 shows a further inexpensive variant of a pump arrangement, as is suitable for use in a brake system according to FIG. 1. Since this pump arrangement does not differ in many features from that according to FIG. 1, only the differences are described here. Parts with the same functions as in FIG. 1 are provided with reference numerals which are reduced by 100.
  • the closing members 128 and 132 of the first suction valve 127 and the second suction valve 131 are commercially available metal balls and are each acted upon in the closing direction by a common valve spring 138 which is arranged between them.
  • the setting of the different admission pressures can take place solely in that the opening cross sections are designed differently.
  • the diameter d of the line of contact of the closing element 128 on the valve seat 129 of the first suction valve 127 is substantially none than the diameter D of the line of contact of the closing element 132 on the valve seat 133 of the second suction valve 131.
  • a further compression spring 139 can open the closing element 132 in the opening direction act so that the spring force of the valve spring is partially canceled.
  • This compression spring 139 can be supported on the screw cap 135. Due to the arrangement of the valve spring 138, which lies in the pressure chamber 122, the valve seat 133 of the second suction valve 131 can be manufactured in one piece with the screw cap 135. The connection for the second suction line runs through the oblique bore 141 placed diagonally in the screw cap 135 into the cavity 142 in the screw cap 135, which is separated from the pressure chamber 122 by the second suction valve 131. If necessary, the compression spring 139 is also arranged in this cavity 142. For reasons of stability, a guide body 140 is attached to the screw cap 135 on the side of the pressure chamber 122 and limits the radial play of the closing element 132 of the second suction valve 131. The guide body 140 is a hollow cylinder which is made in one piece with the screw cap 135.
  • valve seat 133 and screw cover 135 simplifies assembly and further cost savings are achieved by using a common valve spring 138 and by spherical closing members 128 and 132.
  • Figure 3 is divided into part a and part b.
  • Part a shows a longitudinal section through a pump according to the invention, while part b shows a top view of the transmission element used.
  • the pump according to FIG. 3a has housing bore 2 in housing 1, in which delivery piston 3 is guided so that it can be moved and sealed.
  • the delivery piston 3 has a blind-ended longitudinal bore 4, at the end of which it is provided with a transverse bore 5, which opens into a circumferential annular groove 6 on the delivery piston 3.
  • a radial suction connection is created in the housing 1.
  • the valve seat 8 of the suction valve 10 is formed on the delivery piston.
  • the delivery piston 3 has an axial extension 11 radially outside the valve seat 8. This extension 11 is provided with radial openings so as not to impede the pressure medium flow.
  • it has an axial stop bead 12 on which the transmission element 13 is supported and which determines the tilting axes of the lever elements 14 contained in the transmission element 13.
  • the lever element 14 on the transmission element 13 alternates with a large radial extension with the connecting pieces 15, which have only small radial dimensions.
  • the connecting pieces 15 close a ring between the lever elements 14.
  • the lever elements 14 each have an inwardly projecting and an outwardly projecting tongue, the ends of which form the lever arms.
  • the transmission element 13 is preferably formed as a whole from a stamped sheet metal part.
  • the dashed circles shown indicate the contact lines of the functional elements in contact with the transmission element.
  • the circle of the smallest diameter shows the contact line of the valve spring 16.
  • the circle of medium diameter is acted upon by the return spring 17, which presses the transmission element 13 onto the stop bead 12 of the same diameter.
  • the return spring 17 acts from the same axial side on the transmission element 13 as the valve spring 16.
  • a stop sleeve 20, which surrounds the return spring 17, is formed on the closure piece 18 and acts upon the transmission element 13 at the contact line of the largest diameter when the delivery piston 3 moves to the closure piece 18 after the path s has been overcome.
  • the spherical closing member 9, which is arranged between the valve seat 8 and the transmission element 13, is relieved of the force of the valve spring.
  • the bottom dead center is shown in FIG. 3a, so the piston is in its lowest position.
  • the transmission element 13 is not yet in contact with the stop sleeve 20, so that the valve spring 16 acts on the closing element 9 via the transmission element 13 and defines the opening pressure of the suction valve 10.
  • the piston stroke up to the top dead center must be larger than the distance s between the transmission element 13 and the stop sleeve 20th
  • FIG. 4 is divided into parts a, b and c.
  • Part a shows a partial section through a pump, while parts b and c represent one of the transmission elements used.
  • the pump shown in Figure 4a has two suction valves 33 and 34 in the housing 32. They limit the pressure chamber 36 on both axial sides.
  • the suction valve 33 is located on the delivery piston 31, while the suction valve 34 is arranged fixed to the housing on the closure piece 35. Except for the fact that the suction valve 33 is moved with the delivery piston 31, both suction valves 33 and 34 are constructed completely symmetrically.
  • Their closing members 37 and 38 each consist of elastomeric disks, the valve seats 39 and 40 each being formed by an axial, annular bead molded onto the delivery piston 31 and the closure piece 35.
  • a transmission element 41 or 42 is assigned to each of the closing members 37 and 38.
  • the valve spring 43 and the return spring 44 are arranged between the transmission elements 41 and 42.
  • valve spring 43 is also located within the return spring 44 and has the smallest contact radius on the transmission elements 41 and 42, as can also be seen in FIG. 4c by the dashed circles.
  • the return spring 44 is offset radially outward with respect to the stop beads 45 and 46 and, due to its progressive characteristic curve, forms the variable force which leads to the valve spring 43 being tied up at the top dead center of the delivery piston 31.
  • the stop beads 45 and 46 again serve to fix the tilt axes of the transmission elements 41 and 42.
  • the closing members 37 and 38 are freely movable at the top dead center of the delivery piston 31 and are only pressed against their valve seats 39 and 40 by an overpressure, which is determined by the design of the pressure valve, not shown.
  • an overpressure which is determined by the design of the pressure valve, not shown.
  • pressure medium can thus penetrate into the pressure chamber 36 unhindered.
  • the valve spring 43 exerts a greater lever torque on the transmission elements 41 and 42 than the return spring 44, so that the closing members 37 and 38 are acted upon by the force of the valve spring 43 and a certain amount for opening the suction valves 33 and 34 Pressure difference is required.
  • FIG. 4b shows one of the transmission elements 41 and 42 in another sectional plane, from which it emerges how the tongues and recesses shown in FIG. 4c relate to the profile of the transmission elements 41 and 42.
  • the transmission element 41 or 42 shown in plan view in FIG. 2c is divided into three lever elements 47 and three connecting pieces 48 arranged between them.
  • This transmission element differs from that according to FIG. 3 in that, as said, instead of the five lever elements 14 in FIG. 3, it has only three lever elements 47. These lever elements 47 also have a different shape.
  • the tongues pointing inwards do not correspond to tongues pointing outwards, but in these angular areas there are radial recesses on the outer circumference of the transmission element, which increase the flexibility of the transmission element.
  • the lever elements 47 each extend over a larger circumferential area, so that the actual outer lever arm is located on both sides of the recesses along the circumference.
  • the transmission element shown is a molded sheet metal stamped part.
  • FIG. 5 shows a sectional view of the pressure chamber 21 of a pump according to the invention.
  • the delivery piston 3 has a longitudinal bore 4, which is connected to a suction connection, not shown, of the pump.
  • the valve seat 8 of the suction valve 10 is formed on the delivery piston 3.
  • the closing member 49 is provided with an extension 50 which extends in the direction facing away from the delivery piston 3.
  • a valve spring 16 is supported on the one hand on the closing member 49 and on the other hand on a spring plate 51 which has a stop fixed to the housing on the closure piece 18.
  • a pressure channel 19 is arranged in the closure piece 18 and leads to the pressure side of the pump via a pressure valve, not shown.
  • the pressure chamber 21 is delimited by the housing bore 2, the closure piece 18 and the delivery piston 3.
  • a return spring 17 is arranged between the delivery piston 3 and the spring plate 51 and moves the delivery piston 3 in the direction of its bottom dead center.
  • the spring plate 51 has a cylindrical section 52, in which the extension 50 is guided. This guidance takes place via a friction element 54 arranged in a groove 53 of the extension 50.
  • the axial extent of the cylindrical section 52 is greater than the total stroke of the delivery piston 3.
  • Figure 5 shows the delivery piston 3 shortly before reaching top dead center, that is, shortly before the end of the pressure stroke.
  • Pressure medium is conveyed through the pressure channel 19 in the direction of the arrow.
  • the friction element 54 has the effect that a friction force R directed against the bias of the valve spring 16 is exerted on the closing member 49. This results in a smaller resulting prestress.
  • the closing member 49 thus opens at a smaller pressure difference between the longitudinal bore 4 and the pressure chamber 21 than without the action of the force R.
  • FIG. 6 shows a closing member 49 with a body 55 which is not suitable for flow. Only the half to the left of the axis of symmetry is shown; the same components as in FIG. 5 are provided with the same reference symbols.
  • the aerodynamically unfavorable body 55 has the shape of a spherical section, the curved surface 56 of which is arranged in the direction of the pressure channel 19, while its flat rear annular surface 57, which has a large flow resistance, faces the delivery piston 3.
  • the cylindrical section 52 has a larger diameter than in FIG. 5 in order to be able to accommodate the body 55.
  • FIG. 7 shows a section of a pump according to the invention, which has a closing member 49 connected to an inertial body 60.
  • a spring plate was dispensed with here, the return spring 17 and the valve spring 16 are supported directly on the closure piece 18.
  • the inertial body 60 is guided in a hollow cylindrical section 61 of the closure piece 18 and has an essentially cylindrical shape. It tapers towards the closing member 49, so that a step 62 remains on which the valve spring 16 is supported.
  • the compression of the valve spring 16 during the pressure stroke increases the pressure difference required until the top dead center is reached.
  • the working point of the pump can be brought into the range of the resonance of the oscillating spring-mass system by suitable coordination of the mass and the speed of a motor driving the delivery piston 3, in which the required opening pressure is minimal at every point between top and bottom dead center .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Regulating Braking Force (AREA)
  • Reciprocating Pumps (AREA)

Abstract

A hydraulic braking system has a skid control that works according to the feedback principle and a self-priming pump that sucks hydraulic fluid out of a hydraulic fluid container for controlling the drive slip. In order to improve the capacity of the pump with a parallel arrangement of both suction valves, an improved design of the pump arrangement is disclosed, in which both suction valves (227, 231) are integrated in the pump housing (215). Advantageously they are opposite to each other in the axial direction. The first suction valve (227) is located on the movable piston (219) and the second suction valve (231) is linked to a screw cap (235). Also disclosed is a pump for the disclosed skid-controlled hydraulic braking system which has at least one suction valve (10) with a valve seat (8), a closure member (49) and a valve spring (16). The prestress of the valve spring changes depending on the position of a feeding piston (3). Means are provided that are suitable for exerting a force on the closure member (49) which counteracts the force exerted by the valve spring (16) during the suction stroke of the feeding piston (3).

Description

Die Vorliegende Erfindung betrifft eine hydraulische Bremsanlage der im Oberbegriff des Hauptanspruchs beschriebenen Gattung.The present invention relates to a hydraulic brake system of the type described in the preamble of the main claim.

Eine gattungsgemäße Bremsanlage ist aus der DE 34 39 408 C1 bekannt. Die bekannte Bremsanlage arbeitet im Bremsschlupfregelbetrieb nach dem Rückförderprinzip. Die Rückförderpumpe ist selbstansaugend ausgelegt und saugt bei einer Bremsschlupfregelung über ein erstes Saugventil und eine erste Saugleitung aus dem Niederdruckspeicher, während sie zur Antriebsschlupfregelung über ein zweites Saugventil und eine mit einem Umschaltventil versehene zweite Saugleitung über die Bremsleitung und über den Hauptbremszylinder aus dem Druckmittelbehälter ansaugt. Im Vergleich zu anderen Bremsanlagen, bei welchen die beiden Saugleitungen verbunden werden, um über ein gemeinsames Saugventil zur Saugseite der Pumpe zu führen, und bei welchen bei der ersten Saugleitung ein zusätzliches Saugventil angeordnet ist, das verhindert, daß im Niederdruckspeicher Unterdruck entstehen kann, hat die Parallelschaltung der Saugventile den Vorteil, daß sowohl bei einer Bremsschlupfregelung als auch bei einer Antriebsschlupfregelung jeweils nur ein Saugventil überwunden werden muß. Dadurch werden Drosseleffekte vermindert, so daß die Förderleistung der Pumpe verbessert ist.A generic brake system is known from DE 34 39 408 C1. The known brake system works in the brake slip control mode according to the return feed principle. The return pump is self-priming and, in the case of brake slip control, sucks from the low-pressure accumulator via a first suction valve and a first suction line, while it draws in from the pressure medium container via a second suction valve and a second suction line provided with a changeover valve via the brake line and the master brake cylinder. Compared to other brake systems, in which the two suction lines are connected to lead to the suction side of the pump via a common suction valve, and in which an additional suction valve is arranged in the first suction line, which prevents negative pressure from occurring in the low-pressure accumulator the parallel connection of the suction valves has the advantage that only one suction valve has to be overcome in both a brake slip control and a traction control system. Throttling effects are thereby reduced, so that the delivery capacity of the pump is improved.

Eine derartige Pumpe ist beispielsweise aus der DE 40 27 794 A1 bekannt. Die beschriebene Pumpe ist als Radialkolbenpumpe gestaltet und besitzt einen Förderkolben, an welchem der Ventilsitz für das Saugventil angeformt ist. Das Schließglied des Saugventils wird von einer Ventilfeder beaufschlagt, welche sich gehäusefest abstützt. Bei Verkleinerung der Druckkammer durch eine Kolbenbewegung nimmt die Vorspannung der Ventilfeder zu. Am oberen Totpunkt des Kolbens, wenn also die Druckkammer ihr kleinstes Volumen aufweist, ist die Vorspannung der Ventilfeder demnach am größten, so daß ein gegenüber dem unteren Totpunkt des Kolbens wesentlich erhöhter Öffnungsdruck des Saugventils zu überwinden ist.Such a pump is known for example from DE 40 27 794 A1. The pump described is designed as a radial piston pump and has a delivery piston on which the valve seat for the suction valve is molded. The closing element of the suction valve is acted upon by a valve spring which is supported in a housing-fixed manner. When the pressure chamber is reduced by a piston movement, the preload of the valve spring increases. At the top dead center of the piston, that is, when the pressure chamber has its smallest volume, the preload of the valve spring is therefore greatest, so that an opening pressure of the suction valve which is substantially higher than the bottom dead center of the piston has to be overcome.

Um einen gleichbleibenden Öffnungsdruck des Saugventils zu schaffen, ist verschiedentlich schon vorgeschlagen worden, die Ventilfeder des Saugventils zu fesseln. Aber auch dies entspricht noch nicht der optimalen Förderkennlinie einer solchen Pumpe, wenn sie beispielsweise in einer antriebsschlupfgeregelten Bremsanlage eingesetzt werden soll.In order to create a constant opening pressure of the suction valve, various proposals have already been made to tie up the valve spring of the suction valve. But even this does not yet correspond to the optimal delivery characteristic of such a pump if it is to be used, for example, in a traction-controlled brake system.

Die Aufgabe der vorliegenden Erfindung besteht darin, eine konstruktiv günstige Ausgestaltung einer gattungsgemäßen Bremsanlage zu schaffen.The object of the present invention is to provide a structurally advantageous design of a generic brake system.

Eine weitere Aufgabe der vorliegenden Erfindung besteht darin, eine hydraulische Pumpe zu schaffen, bei welcher der Vordruck des Saugventils in der Nähe des oberen Totpunkts des Förderkolbens kleiner ist als in der Nähe des unteren Totpunkts.Another object of the present invention is to provide a hydraulic pump in which the suction valve is less pressurized near the top dead center of the delivery piston than near the bottom dead center.

Gelöst wird diese Aufgabe durch die im Hauptanspruch und in den Unteransprüchen angegebenen Maßnahmen.This task is solved by the measures specified in the main claim and in the subclaims.

Durch die Integration beider Saugventile im Pumpengehäuse ist eine einfache Montage möglich, weil in den Saugleitungen nicht noch zusätzliche Ventile eingefügt werden müssen.By integrating both suction valves in the pump housing, simple installation is possible because additional valves do not have to be inserted in the suction lines.

Eine besonders günstige räumliche Anordnung ergibt sich, wenn eines der Saugventile sich am verschiebbaren Pumpenkolben befindet, während das andere gehäusefest angeordnet ist.A particularly favorable spatial arrangement results if one of the suction valves is located on the displaceable pump piston, while the other is arranged fixed to the housing.

Dabei ist es von Vorteil, die Saugventile axial gegenüberliegend anzuordnen, da damit die axiale Dimensionierung einer zylindrischen Druckkammer unabhängig von der Lage der Saugventile ist.It is advantageous to arrange the suction valves axially opposite, since the axial dimensioning of a cylindrical pressure chamber is thus independent of the position of the suction valves.

Der Unterschied der Vordrücke, welcher zwischen einer Bremsschlupfregelung und einer Antriebsschlupfregelung besteht, kann durch unterschiedliche Auslegung der Öffnungsquerschnitte der Saugventile erfolgen.The difference in the admission pressures, which exists between a brake slip control and a traction control, can take place through different designs of the opening cross sections of the suction valves.

Dadurch ist es dann möglich, beide Schließglieder der Saugventile durch eine gemeinsame Druckfeder in Schließrichtung zu beaufschlagen, da die Öffnungsdrücke durch die unterschiedlichen Öffnungsquerschnitte bestimmt sind.This then makes it possible to act on both closing elements of the suction valves in the closing direction by a common compression spring, since the opening pressures are determined by the different opening cross sections.

Auch bei der Nutzung einer gemeinsamen Druckfeder für beide Schließglieder kann die Belastung des Schließgliedes des zweiten Saugventils dadurch gemindert werden, daß eine zweite Druckfeder, welche schwächer ausgelegt ist, als die zwischen den Schließgliedern angeordnete Druckfeder, letzterer entgegenwirkt.Even when using a common compression spring for both closing members, the load on the closing member of the second suction valve can be reduced by counteracting a second compression spring, which is designed to be weaker than the compression spring arranged between the closing members.

Die Wahl von Kugeln als Schließgliedern ergibt gegenüber speziell ausgeformten Schließgliedern eine Kostenersparnis.The choice of balls as locking elements results in cost savings compared to specially shaped locking elements.

Durch eine Hebelanordnung an der Pumpe nach Anspruch 8 wird im Prinzip eine variable Fesselung der Ventilfeder erzielt. In der Nähe des oberen Totpunktes des Förderkolbens wird die Ventilfeder von den Hebelelementen gehalten, so daß ein Ansaugen mit niedrigem Vordruck schon beim Beginn einer Kolbenbewegung aus dem oberen Totpunkt heraus möglich ist. So trägt die gesamte Druckdifferenz zwischen dem Sauganschluß und der Druckkammer zur Beschleunigung des Druckmittels bei, ohne Einbußen durch zu überwindende Ventilvordrücke. In der Nähe des unteren Totpunktes ist die Ventilfeder ohnehin schon weitgehend entspannt, so daß eine weitere Beaufschlagung durch die Hebelelemente unnötig ist.In principle, variable locking of the valve spring is achieved by means of a lever arrangement on the pump. In the vicinity of the top dead center of the delivery piston, the valve spring is held by the lever elements, so that suction with a low admission pressure is possible from the top dead center at the beginning of a piston movement. The entire pressure difference between the suction connection and the pressure chamber contributes to the acceleration of the pressure medium, without loss of the valve admission pressure to be overcome. In the vicinity of bottom dead center, the valve spring is already largely relaxed anyway, so that further action by the lever elements is unnecessary.

Bei einer raumsparenden Anordnung der Ventilfeder innerhalb einer den Förderkolben zurückstellenden Druckfeder erweist sich eine Beaufschlagung der Hebelelemente nach Anspruch 9 als besonders vorteilhaft. Dabei kann die veränderliche, vom Hub des Förderkolbens abhängige Kraft entweder von der den Förderkolben rückstellenden Druckfeder oder aber von einem gehäusefesten Anschlag erzeugt werden.In a space-saving arrangement of the valve spring within a compression spring returning the delivery piston, an action on the lever elements according to claim 9 proves to be particularly advantageous. The variable force dependent on the stroke of the delivery piston can be generated either by the compression spring returning the delivery piston or by a stop fixed to the housing.

Die Merkmale nach Anspruch 10 ermöglichen einen Einbau der Hebelelemente mit einem Montagevorgang. Durch einstückige Fertigung aller Hebelelemente und der dazwischen angeordneten Verbindungsstücke erübrigt sich eine Vormontage der Hebelanordnung.The features according to claim 10 allow installation of the lever elements with an assembly process. The one-piece production of all lever elements and the connecting pieces arranged between them eliminates the need to preassemble the lever arrangement.

Besonders preiswert wird dieses einstückige Übertragungselement als Blechstanzteil ausgeführt.This one-piece transmission element is particularly inexpensive as a stamped sheet metal part.

Es ist vorgesehen, der durch die Ventilfeder ausgeübten Kraft eine weitere Kraft zu überlagern, deren Größe und Richtung in Abhängigkeit von der Geschwindigkeit und/oder der Beschleunigung des Förderkolbens variieren kann und auf diese Weise ein Öffnen des Ventils während des Saughubs erleichtert.It is envisaged to superimpose a further force on the force exerted by the valve spring, the size and direction of which may vary depending on the speed and / or acceleration of the delivery piston and in this way facilitate opening of the valve during the suction stroke.

Besonders einfach und kostengünstig kann dies durch ein Reibelement erzielt werden, welches einem gewissen Reibungswiderstand auf das Schließglied ausübt welches somit während des Saughubs eine entgegengesetzt zur Ventilfederkraft gerichtete Kraft erfährt. Das Reibelement kann beispielsweise im Bereich eines das Schließglied führenden Elements angeordnet sein.This can be achieved in a particularly simple and cost-effective manner by means of a friction element which exerts a certain frictional resistance on the closing member and which thus experiences a force which is directed counter to the valve spring force during the suction stroke. The friction element can be arranged, for example, in the region of an element guiding the closing element.

Eine zur Geschwindigkeit des Förderkolbens proportionale Zusatzkraft kann erzielt werden, wenn das Schließglied mit einem Körper verbunden ist, der einen großen Strömungswiderstand während der Bewegung vom oberen zum unteren Totpunkt aufweist. Vorteilhafterweise ist dieser Körper in der entgegengesetzten Richtung strömungsgünstiger ausgelegt. Der strömungsungünstige Körper kann einteilig mit dem Schließglied ausgeführt sein.An additional force proportional to the speed of the delivery piston can be achieved if the closing member is connected to a body which has a large flow resistance during the movement from the top to bottom dead center. This body is advantageously designed to be more aerodynamic in the opposite direction. The aerodynamically unfavorable body can be made in one piece with the closing member.

Eine weitere, einfach realisierbare Maßnahme eine Zusatzkraft auf das Schließglied auszuüben besteht darin, das Schließglied mit einem Trägheitskörper zu verbinden, dessen Masse im Vergleich zur Masse des Schließgliedes groß ist. Dabei kann der Trägheitskörper vorteilhafterweise in dem durch die Baulänge der Ventilschließfeder bedingten Totraum angeordnet werden. Zusätzliches Bauvolumen ist somit nicht erforderlich.A further, easily implementable measure of exerting an additional force on the closing element is to connect the closing element to an inertial body, the mass of which is large compared to the mass of the closing element. The inertial body can advantageously be arranged in the dead space caused by the overall length of the valve closing spring. Additional construction volume is therefore not necessary.

Eine über den gesamten Saughub des Förderkolbens konstante, auf das Schließglied wirkende Vorspannkraft kann erzielt werden, wenn die Masse des Trägheitskörpers auf eine Auslegungsdrehzahl eines die Pumpe antreibenden Motors abgestimmt ist.A constant prestressing force acting on the closing member over the entire suction stroke of the delivery piston can be achieved if the mass of the inertial body is matched to a design speed of a motor driving the pump.

Diese Abstimmung erfolgt derart, daß die durch die träge Masse verursachte Kraft und der durch die Kompression der Ventilfeder hervorgerufene variable Anteil an der Federkraft bei vorgegebener Arbeitsdrehzahl so aufeinander abgestimmt werden, daß diese sich aufheben. Bei dieser vorgegebenen Arbeitsdrehzahl kann somit die Förderleistung der Pumpe maximiert werden.This adjustment is carried out in such a way that the force caused by the inertial mass and the variable portion of the spring force caused by the compression of the valve spring are so matched to one another at a predetermined working speed that they cancel each other out. The pump output can thus be maximized at this predetermined working speed.

Es versteht sich, daß sich die einzelnen vorgeschlagenen Maßnahmen auch vorteilhaft kombinieren lassen.It goes without saying that the individual proposed measures can also be advantageously combined.

Eine nähere Erläuterung des Erfindungsgedankens erfolgt nun durch die Beschreibung bevorzugter Ausführungsbeispiele anhand von Zeichnungen. Es zeigt

Fig. 1
eine erfindungsgemäße Bremsanlage
Fig. 2
eine in eine erfindungsgemäße Bremsanlage einfügbare Pumpenanordnung,
Fig. 3
eine weitere, in eine erfindungsgemäße Bremsanlage einfügbare Pumpe, bei welcher sich der Ventilsitz des Saugventils am Förderkolben befindet,
Fig. 4
eine weitere, in eine erfindungsgemäße Bremsanlage einfügbare Pumpe mit zwei Saugventilen, jeweils eines am Förderkolben und eines an einem gehäusefesten Verschlußdeckel,
Fig. 5
Druckkammer einer weiteren, in eine erfindungsgemäße Bremsanlage einfügbaren Pumpe mit Reibelement in geschnittener Darstellung,
Fig. 6
Druckkammer einer weiteren, in eine erfindungsgemäße Bremsanlage einfügbaren Pumpe mit strömungsungünstigem Körper in geschnittener Darstellung,
Fig. 7
Druckkamer einer weiteren, in eine erfindungsgemäße Bremsanlage einfügbaren Pumpe mit Trägheitskörper in geschnittener Darstellung.
A more detailed explanation of the inventive concept will now be given by the description of preferred exemplary embodiments with reference to drawings. It shows
Fig. 1
a brake system according to the invention
Fig. 2
a pump arrangement which can be inserted into a brake system according to the invention,
Fig. 3
another pump which can be inserted into a brake system according to the invention and in which the valve seat of the suction valve is located on the delivery piston,
Fig. 4
another pump that can be inserted into a brake system according to the invention, with two suction valves, one on the delivery piston and one on a closure cover fixed to the housing,
Fig. 5
Pressure chamber of a further pump with friction element, which can be inserted into a brake system according to the invention, in a sectional illustration,
Fig. 6
Pressure chamber of a further pump, which can be inserted into a brake system according to the invention, with a body that is not suitable for flow in a sectional view
Fig. 7
Druckkamer of another, insertable in a brake system according to the invention pump with inertial body in a sectional view.

In Figur 1 ist der Hauptbremszylinder 201 an den Druckmittelbehälter 202 angeschlossen. Vom Hauptbremszylinder 201 führt die Bremsleitung 203 über das elektromagnetisch betätigte, stromlos offene Trennventil 204 und das ebenfalls elektromagnetisch betätigte, stromlos offene Einlaßventil 205 zum Radbremszylinder 206 eines angetriebenen Rades. Vom Radbremszylinder 206 verläuft die Rücklaufleitung 207 über das elektromagnetisch betätigte, stromlos geschlossene Auslaßventil 208 zum Niederdruckspeicher 209. Aus diesem wird über die erste Saugleitung 210 von der Pumpe 211 das Druckmittel in die Druckleitung 212 gefördert, welche zwischen dem Trennventil 204 und dem Einlaßventil 205 in die Bremsleitung 208 mündet. Die zweite Saugleitung 213 der Pumpe 211 ist an die Bremsleitung 203 angeschlossen. In die zweite Saugleitung 213 ist ein hydraulisch vom Druck des Hauptbremszylinders 201 betätigtes, drucklos offenes Umschaltventil 214 eingefügt.In FIG. 1, the master brake cylinder 201 is connected to the pressure medium reservoir 202. The brake line 203 leads from the master brake cylinder 201 via the electromagnetically actuated, normally open isolating valve 204 and the likewise electromagnetically actuated, normally open inlet valve 205 to the wheel brake cylinder 206 of a driven wheel. The return line 207 runs from the wheel brake cylinder 206 via the electromagnetically actuated, normally closed outlet valve 208 to the low-pressure accumulator 209. From this, the pressure medium is conveyed via the first suction line 210 by the pump 211 into the pressure line 212, which between the isolating valve 204 and the inlet valve 205 in the brake line 208 opens. The second suction line 213 of the pump 211 is connected to the brake line 203. A changeover valve 214, which is actuated hydraulically by the pressure of the master brake cylinder 201 and is open without pressure, is inserted into the second suction line 213.

Für die Erfindung ist es unwesentlich, ob die Pumpe 211 über die Bremsleitung 203 und den Hauptbremszylinder 201 aus dem Druckmittelbehälter 202 zur Antriebsschlupfregelung das Druckmittel ansaugt oder ob die zweite Saugleitung 213 direkt an den Druckmittelbehälter 202 angeschlossen ist, da der Hauptbremszylinder 201 in unbetätigtem Zustand vom Druckmittel durchströmt werden kann.It is immaterial for the invention whether the pump 211 sucks the pressure medium from the pressure medium container 202 for traction control via the brake line 203 and the master brake cylinder 201 or whether the second suction line 213 is connected directly to the pressure medium container 202, since the master brake cylinder 201 is in the unactuated state from Pressure medium can be flowed through.

Das Gehäuse 215 der Pumpe 211 besitzt eine durchgehende, einfach gestufte Bohrung 216. Im Bohrungsabschnitt 217 kleineren Durchmessers ist der Kolben 219 gegen die Bohrungswand abgedichtet an die Atmosphäre geführt. Der Bohrungsabschnitt 218 größeren Durchmessers ist mit dem Schraubdeckel 235 druckdicht verschlossen. Zwischen dem bohrungsinneren Ende des Kolbens 219 und der Erweiterungsstufe 220 spannt sich die Druckkammer 222 auf, in welcher die Rückstellfeder 221 angeordnet ist. Diese stützt sich am Ventilsitz 233 des zweiten Saugventils 231 ab und beaufschlagt die bohrungsinnere Stirnseite des Kolbens 219 zur Atmosphäre hin. Vom Bohrungsinneren her ist in den Kolben 219 eine axiale Sackbohrung 223 geführt. Diese ist an ihrem Ende durch die Querbohrung 224 mit der umlaufenden Ringnut 225 verbunden, welche zum ersten Sauganschluß 226 führt, der mit dem Niederdruckspeicher 209 verbunden ist. An der Mündung der Sackbohrung 223 in die Druckkammer 222 ist das erste Saugventil 227 angebracht. Der Ventilsitz 229 des ersten Saugventils 227 ist am Kolbenende angeformt, während das Schließglied 228 von der Ventilfeder 230 zum Ventilsitz hin beaufschlagt wird. Diese Ventilfeder 230 stützt sich wie auch die Rückstellfeder 221 am Ventilsitz 233 des zweiten Saugventils ab. Der Ventilsitz 233 des zweiten Saugventils 231 ist durch die Rastnasen 236 formschlüssig mit dem Schraubdeckel 235 verbunden. Von diesem wird er druckmitteldicht gegen die Erweiterungsstufe 220 gedrückt. Zwischen Ventilsitz 233 und Schraubdeckel 235 ist die Ventilfeder 234 des zweiten Saugventils 231 angeordnet. Sie beaufschlagt eine Ringscheibe, welche mit einem am Schließglied 232 des zweiten Saugventils 231 angeformten Stößel verbunden ist.The housing 215 of the pump 211 has a continuous, simply stepped bore 216. In the bore section 217 of smaller diameter, the piston 219 is guided to the atmosphere in a manner sealed against the bore wall. The bore section 218 of larger diameter is closed pressure-tight with the screw cap 235. The pressure chamber 222, in which the return spring 221 is arranged, spans between the bore-inner end of the piston 219 and the expansion stage 220. This is supported on the valve seat 233 of the second suction valve 231 and acts on the inside of the bore of the piston 219 towards the atmosphere. An axial blind bore 223 is guided into the piston 219 from the inside of the bore. This is connected at its end through the transverse bore 224 to the circumferential annular groove 225, which leads to the first suction connection 226, which is connected to the low-pressure accumulator 209. The first suction valve 227 is attached at the mouth of the blind bore 223 into the pressure chamber 222. The valve seat 229 of the first suction valve 227 is integrally formed on the piston end, while the closing member 228 is acted upon by the valve spring 230 toward the valve seat. Like the return spring 221, this valve spring 230 is supported on the valve seat 233 of the second suction valve. The valve seat 233 of the second suction valve 231 is positively connected to the screw cap 235 by the locking lugs 236. From this he is pressed against the expansion stage 220 in a pressure-tight manner. The valve spring 234 of the second suction valve 231 is arranged between the valve seat 233 and the screw cap 235. It acts on an annular disc which is connected to a plunger formed on the closing element 232 of the second suction valve 231.

Die Ventilfeder 234 stützt sich dazu ebenfalls am ventilsitz 233 ab und beaufschlagt die Ringscheibe zum Schraubdeckel 235 hin.For this purpose, the valve spring 234 is also supported on the valve seat 233 and acts on the annular disc towards the screw cap 235.

Das Schließglied 232 ist dazu teilkugelförmig gestaltet, wobei der Stößel in der Mitte der kugeligen Fläche angebrachte ist. Radial von der Druckkammer 222 führt eine Verbindung zum Druckventil 237 welches über die Druckleitung 212 an die Bremsleitung 203 zwischen Trennventil 204 und Einlaßventil 205 angeschlossen ist.For this purpose, the closing member 232 is designed in the form of a part of a sphere, the plunger being attached in the middle of the spherical surface. Radially from the pressure chamber 222 there is a connection to the pressure valve 237 which is connected via the pressure line 212 to the brake line 203 between the isolation valve 204 and the inlet valve 205.

Der Vordruck der beiden Saugventile 227 und 231 ist zum einen durch den Durchmesser der Ventilsitze 229 und 233 und zum anderen durch die Federkräfte der Ventilfedern 230 und 234 bestimmt. Dabei hat sich für das erste Saugventil 227 ein Vordruck in Höhe des Atmosphärendruckes oder darüber bewährt, da auf diese Weise ein Druckabfall unter Atmosphärendurck im Niederdruckspeicher 209 sowie im Radbremszylinder 206 unterbunden wird. Für das Saugventil 231 ist eine solche Vorsichtsmaßnahme nicht erforderlich, sondern es soll eine möglichst gute Förderleistung erzielt werden. Der Vordruck dieses zweiten Saugventils 231 liegt daher unter Atmosphärendruck, vorzugsweise bei etwa 0,2 bar.The admission pressure of the two suction valves 227 and 231 is determined on the one hand by the diameter of the valve seats 229 and 233 and on the other hand by the spring forces of the valve springs 230 and 234. In this case, a pre-pressure at or above atmospheric pressure has proven itself for the first suction valve 227, since in this way a pressure drop below atmospheric pressure in the low-pressure accumulator 209 and in the wheel brake cylinder 206 is prevented. Such a precautionary measure is not necessary for the suction valve 231, but rather the best possible delivery rate is to be achieved. The upstream pressure of this second suction valve 231 is therefore below atmospheric pressure, preferably around 0.2 bar.

Figur 2 zeigt eine weitere kostengünstige Variante einer Pumpenanordnung, wie sie sich zur Verwendung in einer Bremsanlage nach Figur 1 eignet. Da diese Pumpenanordnung sich in vielen Merkmalen nicht von der nach Figur 1 unterscheidet, werden hier nur die Unterschiede beschrieben. Dabei sind Teile mit gleichen Funktionen wie in Figur 1 mit Bezugszeichen versehen, welche um 100 erniedrigt sind.FIG. 2 shows a further inexpensive variant of a pump arrangement, as is suitable for use in a brake system according to FIG. 1. Since this pump arrangement does not differ in many features from that according to FIG. 1, only the differences are described here. Parts with the same functions as in FIG. 1 are provided with reference numerals which are reduced by 100.

Der wichtigste Unterschied zu Figur 1 besteht darin, daß die Schließglieder 128 und 132 des ersten Saugventils 127 und des zweiten Saugventils 131 handelsübliche Metallkugeln sind und von einer gemeinsamen Ventilfeder 138, welche zwischen ihnen angeordnet ist, jeweils in Schließrichtung beaufschlagt sind. Dabei kann die Einstellung der unterschiedlichen Vordrücke allein dadurch erfolgen, daß die Öffnungsquerschnitte unterschiedlich ausgelegt sind. Das bedeutet, daß der Durchmesser d der Berührungslinie des Schließgliedes 128 am Ventilsitz 129 des ersten Saugventils 127 wesentlich keiner ist als der Durchmesser D der Berührungslinie des Schließgliedes 132 am Ventilsitz 133 des zweiten Saugventils 131. Zusätzlich kann eine weitere Druckfeder 139 das Schließglied 132 in Öffnungsrichtung beaufschlagen, so daß die Federkraft der Ventilfeder zum Teil aufgehoben wird. Diese Druckfeder 139 kann sich am Schraubdeckel 135 abstützen. Durch die Anordnung der Ventilfeder 138, welche in der Druckkammer 122 liegt, kann der Ventilsitz 133 des zweiten Saugventils 131 einteilig mit dem Schraubdeckel 135 gefertigt werden. Der Anschluß für die zweite Saugleitung verläuft durch die diagonal in den Schraubdeckel 135 gelegte Schrägbohrung 141 in den Hohlraum 142 im Schraubdeckel 135, welcher durch das zweite Saugventil 131 von der Druckkammer 122 getrennt ist. In diesem Hohlraum 142 ist - falls erforderlich - auch die Druckfeder 139 angeordnet. Aus Stabilitätsgründen ist am Schraubdeckel 135 auf der Seite der Druckkammer 122 ein Führungskörper 140 angebracht, welcher das radiale Spiel des Schließgliedes 132 des zweiten Saugventils 131 begrenzt. Der Führungskörper 140 ist ein Hohlzylinder, der mit dem Schraubdeckel 135 aus einem Teil gefertigt ist.The most important difference from Figure 1 is that the closing members 128 and 132 of the first suction valve 127 and the second suction valve 131 are commercially available metal balls and are each acted upon in the closing direction by a common valve spring 138 which is arranged between them. The setting of the different admission pressures can take place solely in that the opening cross sections are designed differently. This means that the diameter d of the line of contact of the closing element 128 on the valve seat 129 of the first suction valve 127 is substantially none than the diameter D of the line of contact of the closing element 132 on the valve seat 133 of the second suction valve 131. In addition, a further compression spring 139 can open the closing element 132 in the opening direction act so that the spring force of the valve spring is partially canceled. This compression spring 139 can be supported on the screw cap 135. Due to the arrangement of the valve spring 138, which lies in the pressure chamber 122, the valve seat 133 of the second suction valve 131 can be manufactured in one piece with the screw cap 135. The connection for the second suction line runs through the oblique bore 141 placed diagonally in the screw cap 135 into the cavity 142 in the screw cap 135, which is separated from the pressure chamber 122 by the second suction valve 131. If necessary, the compression spring 139 is also arranged in this cavity 142. For reasons of stability, a guide body 140 is attached to the screw cap 135 on the side of the pressure chamber 122 and limits the radial play of the closing element 132 of the second suction valve 131. The guide body 140 is a hollow cylinder which is made in one piece with the screw cap 135.

Durch die einteilige Fertigung von Ventilsitz 133 und Schraubdeckel 135 ergibt sich eine Montagevereinfachung und durch die Verwendung einer gemeinsamen Ventilfeder 138 sowie durch kugelförmige Schließglieder 128 und 132 eine weitere Kosteneinsparung.The one-piece production of valve seat 133 and screw cover 135 simplifies assembly and further cost savings are achieved by using a common valve spring 138 and by spherical closing members 128 and 132.

Figur 3 ist in einen Teil a und einen Teil b untergliedert. Teil a zeigt einen Längsschnitt durch eine erfindungsgemäße Pumpe, während Teil b das verwendete Übertragungselement in Draufsicht zeigt.Figure 3 is divided into part a and part b. Part a shows a longitudinal section through a pump according to the invention, while part b shows a top view of the transmission element used.

Die Pumpe nach Figur 3a besitzt im Gehäuse 1 die Gehäusebohrung 2, in welcher der Förderkolben 3 abgedichtet verschiebbar geführt ist. Der Förderkolben 3 weist eine blind endende Längsbohrung 4 auf, an deren Ende er mit einer Querbohrung 5 versehen ist, welche in eine umlaufende Ringnut 6 am Förderkolben 3 mündet. Im Axialbereich der Ringnut 6 ist im Gehäuse 1 ein radialer Sauganschluß angelegt. Am offenen Ende der Längsbohrung 4 ist der Ventilsitz 8 des Saugventils 10 am Förderkolben ausgebildet. Zur radialen Führung des Schließgliedes 9 des Saugventils 10 besitzt der Förderkolben 3 radial außerhalb des Ventilsitzes 8 einen axialen Fortsatz 11. Dieser Fortsatz 11 ist mit radialen Durchbrüchen versehen, um den Druckmittelstrom nicht zu behindern. Außerdem besitzt er einen axialen Anschlagwulst 12, an welchem sich das Übertragungselement 13 abstützt und welcher die Kippachsen der im Übertragungselement 13 enthaltenen Hebelelemente 14 bestimmt.The pump according to FIG. 3a has housing bore 2 in housing 1, in which delivery piston 3 is guided so that it can be moved and sealed. The delivery piston 3 has a blind-ended longitudinal bore 4, at the end of which it is provided with a transverse bore 5, which opens into a circumferential annular groove 6 on the delivery piston 3. In the axial area of the annular groove 6, a radial suction connection is created in the housing 1. At the open end of the longitudinal bore 4, the valve seat 8 of the suction valve 10 is formed on the delivery piston. For the radial guidance of the closing member 9 of the suction valve 10, the delivery piston 3 has an axial extension 11 radially outside the valve seat 8. This extension 11 is provided with radial openings so as not to impede the pressure medium flow. In addition, it has an axial stop bead 12 on which the transmission element 13 is supported and which determines the tilting axes of the lever elements 14 contained in the transmission element 13.

Wie in Figur 3b zu erkennen ist, wechseln sich am Übertragungselement 13 die Hebelelement 14 mit großer radialer Ausdehnung ab mit den Verbindungsstücken 15, welche nur geringe radiale Abmessungen haben.As can be seen in FIG. 3b, the lever element 14 on the transmission element 13 alternates with a large radial extension with the connecting pieces 15, which have only small radial dimensions.

Dabei schließen die Verbindungsstücke 15 einen Ring zwischen den Hebelelementen 14. Die Hebelelemente 14 besitzen jeweils eine nach innen ragende und eine nach außen ragende Zunge, deren Enden die Hebelarme bilden. Das Übertragungselement 13 ist vorzugsweise als Ganzes aus einem Blechstanzteil geformt.The connecting pieces 15 close a ring between the lever elements 14. The lever elements 14 each have an inwardly projecting and an outwardly projecting tongue, the ends of which form the lever arms. The transmission element 13 is preferably formed as a whole from a stamped sheet metal part.

Mit den dargestellten gestrichelten Kreisen sind die Anlagelinien der mit dem Übertragungselement in Berührung stehenden Funktionselemente angedeutet. Der Kreis kleinsten Durchmessers zeigt die Anlagelinie der Ventilfeder 16. Der Kreis mittleren Durchmessers wird von der Rückstellfeder 17 beaufschlagt, welche das Übertragungselemenz 13 auf den Anschlagwulst 12 gleichen Durchmessers drückt. Dabei wirkt die Rückstellfeder 17 von derselben axialen Seite auf das Übertragungselement 13 wie die Ventilfeder 16. Als gehäusefester Anschlag für die Ventilfeder 16 und die Rückstellfeder 17 dient das Verschlußstück 18, welches mit einem axialen Druckkanal 19 versehen ist, der zu einem nicht dargestellten Druckventil führt.The dashed circles shown indicate the contact lines of the functional elements in contact with the transmission element. The circle of the smallest diameter shows the contact line of the valve spring 16. The circle of medium diameter is acted upon by the return spring 17, which presses the transmission element 13 onto the stop bead 12 of the same diameter. The return spring 17 acts from the same axial side on the transmission element 13 as the valve spring 16. As a fixed stop for the valve spring 16 and the return spring 17, the closure piece 18, which is provided with an axial pressure channel 19, which leads to a pressure valve, not shown .

An das Verschlußstück 18 ist eine die Rückstellfeder 17 umgebende Anschlaghülse 20 angeformt, welche bei einer Bewegung des Förderkolbens 3 zum Verschlußstück 18 nach Überwindung des Weges s das Übertragungselement 13 an der Berührungslinie größten Durchmessers beaufschlagt. Hierdurch wird die Bewegung der äußeren Zungen der Hebelelemente 14 zum Verschlußstück 18 hin begrenzt, so daß sich das Übertragungselement 13 verformt und die inneren Zungen der Hebelelemente 14 die Ventilfeder 16 zusammendrücken. Das kugelförmige Schließglied 9, welches zwischen dem Ventilsitz 8 und dem Übertragungselement 13 angeordnet ist, wird dadurch von der Kraft der Ventilfeder entlastet.A stop sleeve 20, which surrounds the return spring 17, is formed on the closure piece 18 and acts upon the transmission element 13 at the contact line of the largest diameter when the delivery piston 3 moves to the closure piece 18 after the path s has been overcome. As a result, the movement of the outer tongues of the lever elements 14 toward the closure piece 18 is limited, so that the transmission element 13 deforms and the inner tongues of the lever elements 14 compress the valve spring 16. The spherical closing member 9, which is arranged between the valve seat 8 and the transmission element 13, is relieved of the force of the valve spring.

In der Figur 3a ist der untere Totpunkt dargestellt, der Kolben befindet sich also in seiner tiefsten Position. Das heißt, daß die Druckkammer 21, welche von der Rückstellfeder 17 aufgespannt wird, ihr größtes Volumen hat. Das Übertragungselement 13 ist noch nicht in Kontakt mit der Anschlaghülse 20, so daß die Ventilfeder 16 über das Übertragungselement 13 auf das Schließglied 9 einwirkt und den Öffnungsdruck des Saugventils 10 festlegt. Der Kolbenhub bis zum oberen Totpunkt muß größer bemessen sein als der Abstand s zwischen dem Übertragungselement 13 und der Anschlaghülse 20.The bottom dead center is shown in FIG. 3a, so the piston is in its lowest position. This means that the pressure chamber 21, which is opened by the return spring 17, has its largest volume. The transmission element 13 is not yet in contact with the stop sleeve 20, so that the valve spring 16 acts on the closing element 9 via the transmission element 13 and defines the opening pressure of the suction valve 10. The piston stroke up to the top dead center must be larger than the distance s between the transmission element 13 and the stop sleeve 20th

Figur 4 ist in die Teile a, b und c untergliedert. Teil a zeigt einen Teilschnitt durch eine Pumpe, während Teil b und c eins der verwendeten Übertragungselemente darstellen. Die in Figur 4a gezeigte Pumpe besitzt zwei Saugventile 33 und 34 im Gehäuse 32. Sie begrenzen die Druckkammer 36 auf beiden axialen Seiten. Dabei befindet sich das Saugventil 33 am Förderkolben 31, während das Saugventil 34 gehäusefest am Verschlußstück 35 angeordnet ist. Bis auf die Tatsache, daß das Saugventil 33 mit dem Förderkolben 31 bewegt wird, sind beide Saugventile 33 und 34 völlig symmetrisch aufgebaut. Ihre Schließglieder 37 und 38 bestehen jeweils auf elastomeren Scheiben, wobei die Ventilsitze 39 und 40 jeweils von einem am Förderkolben 31 bzw. am Verschlußstück 35 angeformten axialen, ringförmigen Wulst gebildet werden.Figure 4 is divided into parts a, b and c. Part a shows a partial section through a pump, while parts b and c represent one of the transmission elements used. The pump shown in Figure 4a has two suction valves 33 and 34 in the housing 32. They limit the pressure chamber 36 on both axial sides. The suction valve 33 is located on the delivery piston 31, while the suction valve 34 is arranged fixed to the housing on the closure piece 35. Except for the fact that the suction valve 33 is moved with the delivery piston 31, both suction valves 33 and 34 are constructed completely symmetrically. Their closing members 37 and 38 each consist of elastomeric disks, the valve seats 39 and 40 each being formed by an axial, annular bead molded onto the delivery piston 31 and the closure piece 35.

Jedem der Schließglieder 37 und 38 ist ein Übertragungselement 41 bzw. 42 zugeordnet. Zwischen den Übertragungselementen 41 und 42 sind die Ventilfeder 43 und die Rückstellfeder 44 angeordnet.A transmission element 41 or 42 is assigned to each of the closing members 37 and 38. The valve spring 43 and the return spring 44 are arranged between the transmission elements 41 and 42.

Wie in Figur 1 befindet sich auch hier die Ventilfeder 43 innerhalb der Rückstellfeder 44 und besitzt an den Übertragungselementen 41 und 42 jeweils den kleinsten Anlageradius, wie auch in Figur 4c anhand der gestrichelten Kreise erkennbar ist. Die Rückstellfeder 44 ist hier gegenüber den Anschlagwulsten 45 und 46 radial nach außen versetzt und bildet durch ihre progressive Kennlinie die variable Kraft, welche am oberen Totpunkt des Förderkolbens 31 zur Fesselung der Ventilfeder 43 führt. Die Anschlagwulste 45 und 46 dienen dabei wieder zur Festsetzung der Kippachsen der Übertragungselemente 41 und 42.As in FIG. 1, the valve spring 43 is also located within the return spring 44 and has the smallest contact radius on the transmission elements 41 and 42, as can also be seen in FIG. 4c by the dashed circles. The return spring 44 is offset radially outward with respect to the stop beads 45 and 46 and, due to its progressive characteristic curve, forms the variable force which leads to the valve spring 43 being tied up at the top dead center of the delivery piston 31. The stop beads 45 and 46 again serve to fix the tilt axes of the transmission elements 41 and 42.

Wie die linke Bildhälfte von Figur 4a zeigt, sind am oberen Totpunkt des Förderkolbens 31 die Schließglieder 37 und 38 frei beweglich und werden nur durch einen Überdruck, welcher durch die Auslegung des nicht dargestellten Druckventils bestimmt ist, an ihre Ventilsitze 39 bzw. 40 gedrückt. Sobald sich der Förderkolben 31 auf seinen in der rechten Bildhälfte dargestellten unteren Totpunkt zubewegt, kann also Druckmittel ungehindert in die Druckkammer 36 eindringen. Am unteren Totpunkt des Förderkolbens jedoch übt die Ventilfeder 43 auf die Übertragungselement 41 und 42 ein größeres Hebelmoment aus als die Rückstellfeder 44, so daß die Schließglieder 37 und 38 von der Kraft der Ventilfeder 43 beaufschlagt werden und zum Öffnen der Saugventile 33 und 34 eine gewisse Druckdifferenz erforderlich ist.As the left half of Figure 4a shows, the closing members 37 and 38 are freely movable at the top dead center of the delivery piston 31 and are only pressed against their valve seats 39 and 40 by an overpressure, which is determined by the design of the pressure valve, not shown. As soon as the delivery piston 31 moves to its bottom dead center shown in the right half of the figure, pressure medium can thus penetrate into the pressure chamber 36 unhindered. At the bottom dead center of the delivery piston, however, the valve spring 43 exerts a greater lever torque on the transmission elements 41 and 42 than the return spring 44, so that the closing members 37 and 38 are acted upon by the force of the valve spring 43 and a certain amount for opening the suction valves 33 and 34 Pressure difference is required.

Figur 4b zeigt eines der Übertragungselemente 41 und 42 in einer anderen Schnittebene, aus welcher hervorgeht, wie sich die in Figur 4c dargestellten Zungen und Ausnehmungen zum Profil der Übertragungselemente 41 und 42 verhalten.FIG. 4b shows one of the transmission elements 41 and 42 in another sectional plane, from which it emerges how the tongues and recesses shown in FIG. 4c relate to the profile of the transmission elements 41 and 42.

Das in Figur 2c in Draufsicht gezeigte Übertragungselement 41 oder 42 ist in drei Hebelelemente 47 und drei dazwischen angeordnete Verbindungsstücke 48 unterteilt. Dieses Übertragungselement unterscheidet sich von dem nach Figur 3 dadurch, daß es, wie gesagt, statt der fünf Hebelelemente 14 in Figur 3 nur drei Hebelelemente 47 aufweist. Auch haben diese Hebelelemente 47 eine andere Form.The transmission element 41 or 42 shown in plan view in FIG. 2c is divided into three lever elements 47 and three connecting pieces 48 arranged between them. This transmission element differs from that according to FIG. 3 in that, as said, instead of the five lever elements 14 in FIG. 3, it has only three lever elements 47. These lever elements 47 also have a different shape.

Den nach innen weisenden Zungen entsprechen keine nach außen weisende Zungen, sondern in diesen Winkelbereichen sind am äußeren Umfang des Übertragungselementes radiale Ausnehmungen vorhanden, welche die Biegbarkeit des Übertragungselementes erhöhen. Dafür erstrecken sich die Hebelelemente 47 jeweils über einen größeren Umfangsbereich, so daß der eigentliche äußere Hebelarm sich auf beiden Seiten der Ausnehmungen am Umfang entlang befindet. Wie in Figur 3 ist das dargestellte Übertragungselement ein geformtes Blechstanzteil.The tongues pointing inwards do not correspond to tongues pointing outwards, but in these angular areas there are radial recesses on the outer circumference of the transmission element, which increase the flexibility of the transmission element. For this purpose, the lever elements 47 each extend over a larger circumferential area, so that the actual outer lever arm is located on both sides of the recesses along the circumference. As in Figure 3, the transmission element shown is a molded sheet metal stamped part.

Figur 5 zeigt in geschnittener Darstellung die Druckkammer 21 einer erfindungsgemäßen Pumpe. Im nur teilweise dargestellten Gehäuse 1 der Pumpe befindet sich eine Gehäusebohrung 2 in welcher der Förderkolben 3 abgedichtet verschiebbar geführt ist. Der Förderkolben 3 weist eine Längsbohrung 4 auf, die mit einem nicht dargestellten Sauganschluß der Pumpe in Verbindung steht. Am oberen Ende der Längsbohrung 4 ist der Ventilsitz 8 des Saugventils 10 am Förderkolben 3 ausgebildet. Das Schließglied 49 ist mit einem Fortsatz 50 versehen, der sich in der vom Förderkolben 3 abgewandten Richtung erstreckt. Eine Ventilfeder 16 stützt sich einerseits am Schließglied 49 und andererseits an einem Federteller 51 ab, der einen gehäusefesten Anschlag am Verschlußstück 18 hat. Im Verschlußstück 18 ist ein Druckkanal 19 angeordnet, der über ein nicht dargestelltes Druckventil zur Druckseite der Pumpe führt.Figure 5 shows a sectional view of the pressure chamber 21 of a pump according to the invention. In the housing 1 of the pump, which is only partially shown, there is a housing bore 2 in which the delivery piston 3 is guided in a sealed, displaceable manner. The delivery piston 3 has a longitudinal bore 4, which is connected to a suction connection, not shown, of the pump. At the upper end of the longitudinal bore 4, the valve seat 8 of the suction valve 10 is formed on the delivery piston 3. The closing member 49 is provided with an extension 50 which extends in the direction facing away from the delivery piston 3. A valve spring 16 is supported on the one hand on the closing member 49 and on the other hand on a spring plate 51 which has a stop fixed to the housing on the closure piece 18. A pressure channel 19 is arranged in the closure piece 18 and leads to the pressure side of the pump via a pressure valve, not shown.

Die Druckkammer 21 wird durch die Gehäusebohrung 2, das Verschlußstück 18 und den Förderkolben 3 begrenzt. Zwischen Förderkolben 3 und Federteller 51 ist eine Rückstellfeder 17 angeordnet, die den Förderkolben 3 in Richtung seines unteren Totpunktes verschiebt.The pressure chamber 21 is delimited by the housing bore 2, the closure piece 18 and the delivery piston 3. A return spring 17 is arranged between the delivery piston 3 and the spring plate 51 and moves the delivery piston 3 in the direction of its bottom dead center.

Der Federteller 51 weist einen zylindrischen Abschnitt 52 auf, in dem der Fortsatz 50 geführt ist. Diese Führung erfolgt über ein in einer Nut 53 des Fortsatzes 50 angeordnetes Reibelement 54. Die axiale Ausdehnung des zylindrischen Abschnittes 52 ist größer als der gesamt Hub des Förderkolbens 3.The spring plate 51 has a cylindrical section 52, in which the extension 50 is guided. This guidance takes place via a friction element 54 arranged in a groove 53 of the extension 50. The axial extent of the cylindrical section 52 is greater than the total stroke of the delivery piston 3.

Figur 5 zeigt den Förderkolben 3 kurz vor Erreichen des oberen Totpunkts, das heißt kurz vor Ende des Druckhubs. Druckmittel wird durch den Druckkanal 19 in Richtung des Pfeils gefördert. Nach Erreichen des oberen Totpunkts kehrt sich die Bewegungsrichtung des Förderkolbens 3 um, er bewegt sich in der Abbildung nach unten. Dabei bewirkt das Reibelement 54, daß auf das Schließglied 49 eine entgegen der Vorspannung der Ventilfeder 16 gerichtete Reibungskraft R ausgeübt wird. Es ergibt sich somit eine kleinere resultierende Vorspannung. Das Schließglied 49 öffnet somit bereits bei einer zwischen Längsbohrung 4 und Druckkammer 21 herrschenden kleineren Druckdifferenz als ohne Wirkung der Kraft R.Figure 5 shows the delivery piston 3 shortly before reaching top dead center, that is, shortly before the end of the pressure stroke. Pressure medium is conveyed through the pressure channel 19 in the direction of the arrow. After reaching top dead center, the direction of movement of the delivery piston 3 is reversed and moves downward in the illustration. The friction element 54 has the effect that a friction force R directed against the bias of the valve spring 16 is exerted on the closing member 49. This results in a smaller resulting prestress. The closing member 49 thus opens at a smaller pressure difference between the longitudinal bore 4 and the pressure chamber 21 than without the action of the force R.

Figur 6 zeigt ein Schließglied 49 mit strömungsungünstigem Körper 55. Dabei ist nur die links der Symmetriachse liegende Hälfte abgebildet, gleiche Bauteile wie zu Figur 5 sind mit gleichen Bezugszeichen versehen. Der strömungsungünstige Körper 55 besitzt die Form eines Kugelabschnitts, dessen gewölbte Fläche 56 in Richtung des Druckkanals 19 angeordnet ist, während seine ebene, einen großen Strömungswiderstand aufweisende rückwärtige Ringfläche 57 dem Förderkolben 3 zugewandt ist. der zylindrische Abschnitt 52 weist einen größeren Durchmesser als in Figur 5 auf, um den Körper 55 aufnehmen zu können.FIG. 6 shows a closing member 49 with a body 55 which is not suitable for flow. Only the half to the left of the axis of symmetry is shown; the same components as in FIG. 5 are provided with the same reference symbols. The aerodynamically unfavorable body 55 has the shape of a spherical section, the curved surface 56 of which is arranged in the direction of the pressure channel 19, while its flat rear annular surface 57, which has a large flow resistance, faces the delivery piston 3. the cylindrical section 52 has a larger diameter than in FIG. 5 in order to be able to accommodate the body 55.

Er ist mit einer Verjüngung 58 versehen, an der sich die Ventilfeder 16 abstützt.It is provided with a taper 58 on which the valve spring 16 is supported.

Während des Saughubs des Förderkolbens 3 staut sich im Bereich 59 unterhalb der Ringfläche 57 Druckmittel auf, wodurch eine hydraulisch hervorgerufenen Kraft H auf dem Körper 55 wirkt, die der Vorspannkraft der Ventilfeder 16 entgegenwirkt und somit ein Öffnen des Saugventils 10 bereits bei geringer Druckdifferenz zwischen Längsbohrung 4 und Druckkammer 21 ermöglicht.During the suction stroke of the delivery piston 3, pressure medium builds up in the area 59 below the annular surface 57, as a result of which a hydraulically induced force H acts on the body 55, which counteracts the pretensioning force of the valve spring 16 and thus opens the suction valve 10 even with a small pressure difference between the longitudinal bore 4 and pressure chamber 21 allows.

Figur 7 zeigt einen Ausschnitt einer erfindungsgemäßen Pumpe, die ein mit einem Trägheitskörper 60 verbundenes Schließglied 49 aufweist. Auch hier sind gleiche Teile mit gleichen Bezugszeichen wie zu den vorhergehenden Figuren versehen. Auf einen Federteller wurde hier verzichtet, die Rückstellfeder 17 und die Ventilfeder 16 stützen sich direkt am Verschlußstück 18 ab. Der Trägheitskörper 60 wird in einem hohlzylindrischen Abschnitt 61 des Verschlußstückes 18 geführt und weist eine im wesentlichen zylindrische Form auf. Er verjüngt sich zum Schließglied 49 hin, so daß eine Stufe 62 verbleibt, an der sich die Ventilfeder 16 abstützt.FIG. 7 shows a section of a pump according to the invention, which has a closing member 49 connected to an inertial body 60. Here too, the same parts are provided with the same reference numerals as in the previous figures. A spring plate was dispensed with here, the return spring 17 and the valve spring 16 are supported directly on the closure piece 18. The inertial body 60 is guided in a hollow cylindrical section 61 of the closure piece 18 and has an essentially cylindrical shape. It tapers towards the closing member 49, so that a step 62 remains on which the valve spring 16 is supported.

Die Stärke der Ventilfeder 16 ist so bemessen, daß im unteren Totpunkt ein zwischen Längsbohrung 4 und Druckkammer 21 herrschende Druckunterschied von p = 50 ... 100 mbar ausreicht, das Saugventil 10 zu öffnen. Durch die Kompression der Ventilfeder 16 während des Druckhubs erhöht sich die erforderliche Druckdifferenz bis zum Erreichen des oberen Totpunkts.The strength of the valve spring 16 is dimensioned such that a pressure difference of p = 50 ... 100 mbar prevailing between the longitudinal bore 4 and the pressure chamber 21 at the bottom dead center is sufficient to open the suction valve 10. The compression of the valve spring 16 during the pressure stroke increases the pressure difference required until the top dead center is reached.

Die durch die Masse des Trägheitskörpers 60 hervorgerufene Zusatzkraft wirkt der durch die Ventilfeder 16 ausgeübten Kraft entgegen, sie ist am größten im Bereich des oberen Totpunkts und am kleinsten im Bereich des unteren Totpunkts.The additional force caused by the mass of the inertial body 60 counteracts the force exerted by the valve spring 16, it is greatest in the area of top dead center and smallest in the area of bottom dead center.

Durch geeignete Abstimmung der Masse und der Drehzahl eines den Förderkolben 3 antreibenden Motors kann man den Arbeitspunkt der Pumpe in den Bereich der Resonanz des schwingenden Feder-Masse-Systems bringen, in dem der erforderliche Öffnungsdruck in jedem zwischen oberem und unterem Totpunkt liegenden Punkt minimal ist.The working point of the pump can be brought into the range of the resonance of the oscillating spring-mass system by suitable coordination of the mass and the speed of a motor driving the delivery piston 3, in which the required opening pressure is minimal at every point between top and bottom dead center .

Besonders empfehlenswert ist eine derartige "resonante" Auslegung auf eine hohe Drehzahl knapp unterhalb der Leerlaufdrehzahl des die Pumpe antreibenden Motors, da in diesem Fall bei einer Antriebsschlupfregelung der größte Volumenstrom zum Druckaufbau erforderlich ist.Such a "resonant" design for a high speed just below the idling speed of the motor driving the pump is particularly recommendable, since in this case the greatest volume flow is required for pressure build-up with traction control.

Claims (17)

  1. Hydraulic brake system with brake slip control and traction slip control, including a master brake cylinder (201) which is connected to a pressure fluid reservoir (202), at least one wheel brake cylinder (206) associated with a driven wheel, a brake line (203) from the master brake cylinder (201) to the wheel brake cylinder (206), an inlet valve (205) in the brake line (203), a low-pressure accumulator (209), a return line (207) from the wheel brake cylinder (206) to the low-pressure accumulator (209), an outlet valve (208) in the return line (207), a self-priming pump (211), a pressure chamber (222) in a housing (215), a cut-off valve (204) in the brake line (203) between the master brake cylinder (201) and the inlet valve (205), a pressure line (212) from the pressure chamber (222) to the brake line (203) between the cut-off valve (204) and the inlet valve (205), a pressure valve (237) between the pressure chamber (222) and the pressure line (212), a first suction line (210) between the low-pressure accumulator (209) and the pressure chamber (222), a second suction line (213) between the pressure fluid reservoir (202) and the pressure chamber (222), a change-over valve (214) in the second suction line (213), a first suction valve (227) between the low-pressure accumulator (209) and the pressure chamber (222), a second suction valve (231) between the change-over valve (214) and the pressure chamber (222),
    characterized in that the two suction valves (227, 231) are arranged in the pump housing (215).
  2. Hydraulic brake system as claimed in claim 1,
    characterized in that one (231, 131) of the suction valves (227, 127; 231, 131) has a valve seat (233, 133) on the housing, and the other suction valve (227, 127) has its valve seat (229, 129) on a movable piston (219).
  3. Hydraulic brake system as claimed in claim 1 or claim 2,
    characterized in that the pressure chamber (222, 122) is substantially cylindrical and is defined at each axial end by one suction valve (227, 127; 231, 131).
  4. Hydraulic brake system as claimed in any one of the preceding claims,
    characterized in that the closure member (232, 132) of the second suction valve (231, 131) is acted upon in the opening direction by the pressure in the second suction line (213) on a larger surface (diameter D) than the closure member (228, 128) of the second suction valve (227, 127) is acted upon by the pressure in the first suction line (210).
  5. Hydraulic brake system as claimed in any one of the preceding claims,
    characterized in that a valve spring (138) is interposed between the closure members (128, 132) of the two suction valves (127, 131) and acts upon both closure members (128, 132) in the direction so as to close.
  6. Hydraulic brake system as claimed in claim 5,
    characterized in that the closure member (132) of the second suction valve (131) is acted upon by a compression spring (139) which counteracts the valve spring (138) and is weaker than the valve spring.
  7. Hydraulic brake system as claimed in any one of the preceding claims,
    characterized in that the closure members (128, 132) of both suction valves (127, 131) are balls.
  8. Hydraulic brake system as claimed in any one of the preceding claims, including a pump comprising a housing (1, 32), a substantially cylindrical housing bore (2), a delivery piston (3, 31) movable in the housing bore and at least one suction valve (10, 33, 34) with a valve seat (8, 39, 40), a closure member (9, 37, 38) and a valve spring (16, 43) having a preload which is variable in response to the position of the delivery piston (3, 31), the delivery piston (3, 31) confining a pressure chamber (21, 36) and having a lower dead center where the pressure chamber (21, 36) has its largest volume, and an upper dead center where the pressure chamber (21, 36) has its smallest volume,
    characterized in that, for transmitting the force of the valve spring (16, 43) to the closure member (9, 37, 38) of the suction valve (10, 33, 34), a plurality of lever elements (14, 47) are provided which are spread over the periphery and each extend in a radial direction, the tilting axis of the lever elements extending in a tangential direction, and the lever elements compressing the valve spring (16, 43) proximate the upper dead center.
  9. Hydraulic brake system as claimed in claim 8,
    characterized in that the lever elements (14, 47), when viewed from the center axis of the bore (2), have three abutment radii, the smallest radius being acted upon by the valve spring (16, 43), the intermediate radius abutting on a stop part (stop bead 12, 45) that is rigidly connected to the valve seat (8, 39, 40) and defines the tilting axis, and the external radius being acted upon by a force which is variable in response to the position of the delivery piston (3, 31) and counteracts the lever momentum exerted on the lever elements (14, 47) by the valve spring (16, 43).
  10. Hydraulic brake system as claimed in claim 8 or 9,
    characterized in that the lever elements (14, 47) are interconnected by way of tangentially arranged connecting portions (15, 48) which keep the distances between the lever elements (14, 47) constant along the periphery.
  11. Hydraulic brake system as claimed in claim 10,
    characterized in that the lever elements (14, 47) and the connecting portions (15, 48) are formed integrally as one transmitting element (13, 41, 42).
  12. Hydraulic brake system as claimed in claim 10,
    characterized in that the transmitting element (13, 41, 42) is a sheet-metal punched part.
  13. Hydraulic brake system as claimed in any one of claims 1 to 12, including a pump comprising a housing (1), a substantially cylindrical housing bore (2), a delivery piston (3) movable in the housing bore and at least one suction valve (10) with a valve seat (8), a closure member (49) and a valve spring (16) having a preload which is variable in response to the position of the delivery piston (3), the delivery piston (3) confining a pressure chamber (21) and having a lower dead center where the pressure chamber (21) has its largest volume, and an upper dead center where the pressure chamber (21) has its smallest volume,
    characterized in that a means is provided capable of exerting a force on the closure member (49) which counteracts the force that is exerted by the valve spring (16) during the suction stroke of the delivery piston (3).
  14. Hydraulic brake system as claimed in claim 13,
    characterized in that this means is a friction element (54) which is interposed between the closure member (49) and a component (51) which is not moved along with the delivery piston (3).
  15. Hydraulic brake system as claimed in claim 13,
    characterized in that this means is an aerodynamically unfavorable element (55) which is connected to the closure member (49).
  16. Hydraulic brake system as claimed in claim 13,
    characterized in that this means is an inertia member (60) connected to the closure member (49).
  17. Hydraulic brake system as claimed in claim 16,
    characterized in that the mass of the inertia member (60) is conformed to the rating of the rotational speed of a motor driving the pump.
EP19940921652 1993-07-23 1994-07-16 Hydraulic braking system with skid and drive slip control Expired - Lifetime EP0708721B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE4324689 1993-07-23
DE19934324689 DE4324689A1 (en) 1993-07-23 1993-07-23 Hydraulic brake system with brake slip and traction control
DE19934326389 DE4326389A1 (en) 1993-08-06 1993-08-06 Hydraulic pump
DE4326389 1993-08-06
PCT/EP1994/002350 WO1995003198A1 (en) 1993-07-23 1994-07-16 Hydraulic braking system with skid and drive slip control

Publications (2)

Publication Number Publication Date
EP0708721A1 EP0708721A1 (en) 1996-05-01
EP0708721B1 true EP0708721B1 (en) 1997-03-12

Family

ID=25927935

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19940921652 Expired - Lifetime EP0708721B1 (en) 1993-07-23 1994-07-16 Hydraulic braking system with skid and drive slip control

Country Status (5)

Country Link
US (2) US5722738A (en)
EP (1) EP0708721B1 (en)
JP (1) JPH10507982A (en)
DE (1) DE59402095D1 (en)
WO (1) WO1995003198A1 (en)

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Also Published As

Publication number Publication date
US5722738A (en) 1998-03-03
WO1995003198A1 (en) 1995-02-02
JPH10507982A (en) 1998-08-04
US5984651A (en) 1999-11-16
DE59402095D1 (en) 1997-04-17
EP0708721A1 (en) 1996-05-01

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